Loud-speaking telephone system.



J. J. COMER.' LOUD SPEAKING 'I'ELBPHONE SYSTEM. APPLICATION' FILED 11011.28, 1910.

Patented Jan.l 13, 1914.

a SHEETS-SHEET 1. i

J. J." COMER.

LOUD SPEAKING TELEPHONE SYSTEM.

APPLICATION FILED NOV. 28, 1910.

Patnted Jan 13, 1914.

IAIILIIVV!) I l l l l lir MTA/55555 J. J.COMER. LOUD SPEAKING TELEPHONE' SYSTEM,

` APPLICATION FILED NOV.28, 1910. 1,084,970, Patented Jan. 13, 1914.

3 SHEETS-SHEET 3.

TTOR/VEYS;

l UNITED; STATES PATENT-ermee 4 IJenn J. COMER, or cHIcAGo, ILLINOIS, AssIeNoR To AUTOMATIC ENUNCIATOR CoM-.

PANY, F CHICAGO, ILLINOIS, .A CORPORATIONv OF ILIIIITIS.A

L0UID-SIEEAKIN(irv TELEPHONE SYSTEM.

To allwhom it may concerne: i

Beit known that I, JOHN JCOMR, a

l citizen ofthe United AStates of America, and resident of Chicago,` Cook county, Illinois,

have'ii'ivent'ed a'certain new and useful Im- .provement in Loud Speaking Telephone Systems, of )vhich-'tlie following is a specication.

My invent-ionrelates to'telephone systems ingeneral, but more particularly to systems V'for loud speaking purposes, or similar sys- Vclearne'ss of enunciation efficient loud speaking system', of suchcharact'er that it may be u sed for enunciatin .at

:a distance, er for musical purposes, eier vocal or instrumental, andl may be employed in 4various other -W-ays for which the ,ordi-v nary systemis not adapted; a

l l desirable, When used for loud speakingpur-- -poses.

l tion and this kind;

1- A specialobject is to provide a system'vin Which. the instruments are adapted to operate satisfactorily with heavy currents, as is Anotherobject is to provide a system in 4which provision -is made for accurate adjustment of the different .Instrumentalities to 11isure rthe best. results..

vAnother object 1s to insure clear'enuncla- .It-is also anobject to provide'certain details `and combina-tions tending to increase the general efficiency and render a system of sietfforth and'claimed.

- in a vsystem embodying .the principlesof iny- Aillustrating the manner in which resistancejcanbejemployed in place of capacity to o b- Fig. 3 is a Vieta similar.- to Fig. l, but showing a different ar'- In the accompanyingdrawings Figure V1 and purity of tone' pure tone in' the useof a system ofv vSpecification of Letters Patent.

` this ltind entirely practical -for loudspeak- 'ing and other similar purposes T,o the foregoing and other useful ends, 'jmy invention consists in matters hereinafter shoivs ifa differential transmitter-toonuected With a loudf speaking receiver, together I vith a source of current and connections therefor invention.- Fig. 2 is a View similar to F ig.l,

tain .the desired result.

rangement of the resi-stance: through 4which current is supplied from the'battery to the Patented J an. 13,

n ppiication'iedNovemberas,1910.*Seria1No-594A18- 'transmitter'. F igs. 4, '-5, 6,7 S'an'd 9' arcsec-- tional views'showing Adifferent forms ofdifferential microphone transmitters. FigulOff is an enlarged longitudinal section of 'the operative' portion of the loudspealting "receiveremployed in my said loud speaking system. Fig. 1l is a similar vieu' of the ydifferential microphone repeater einployedVin said system.

As shown In fFiggl, the dil'erentialmicro- .phoneA has the front and! back electrodes a anda andV the intermediate elect-rode u2.

ing coil Z2, one terminal of which is lconnected to the electrode a2, and the otherltern'nnal of which is connected between theconr a, andthe other: polel is connected to lthe elect-rode af, the. lamps .c and e als'resistance at each side lof said battery. vith this arrangement-the receiver B responds Vto the -diierentlal `action of the.

mi'crophone, by reason of the alternate'dis- In ether-'Words one pole yof the' The-loudspeaking receiver B has an operatserving eharge of thecondensers C. and D, due to' the alternaterise andl fall of' the resistance at opposite sides of the electrode a2, in the manner common to diiferential transmitters.

In Fig-2, the arrangement is substantially the same as that shown i-n Fig. l, except that in this case lamps, or other. resistance d'e- 'vices, I and I are substituted for the condensers C and I),'in the manner shown.

,Also, in this case resistance I2 is connected.

in the circuit from one poleof the battery tothe front electrode a, and a lesser resistance I3 is connected in the circuit between the other pole of the battery and the electreden. In this Way the differential action of the transmitter is... e1nployed to operate the receiver.

In Fig., 3, the

arrangement isexactl)v like that shown in Fig. l, with theexception that inthis case resistance J is included inthe circuit between one lpole of the bnttervand vthe electrode a, and'resistance J is included in thepcircuit between the other pole of the battery and the. electrode a.' ;\lso,in this case -ajresistance J2 is connected in` bridge of the battery circuit. and in' multiplewith the condenscrs C and D. This arrangement,

ent i ll iiiuil. alti 'Y `.ernial action of the trans- 1 wijt' operate the receiver.-

. therefore, that many differ- Ue employed for connecting the ..iil'erenttal transmitter with a loud speaking receiver, or with a re seater, and

that for this reason I do not limit mvselt to electrodes a. and aare vibrator-y with the said box, and the middle electrode a2, which separates the chamber of the box into, two compartments, is also vibratory withl said diaphragm and vsaid boX. The stationary electrodes o5 and alare carried on a stem o8,

which latter is adjustably connected to the bridge o9, which latter is insulated from the 'balance of the structure.

back electrodes are applied with micainsu lations, and the box is also lined with lnica carry heavy currents and becomef'quite hot withoutinjury thereto. I t will be observed that the granular carbon is the only. medium of connection to y or fromthe' electrodes a and aT-that is to say, thesetwo electrodes are electrically connectedI on the stem by which they are mounted, and current canl only pass to or l trom these electrodes by tir-st passing througl'i the granular carbon. In Fig. 5, the stationary box a, is mounted on the plate a and contains the front and back electrodes@ and a', the granular carbon of', and the intermediate electrode a2, as prevn viously described. The electrode@2 is connected with the diaphragm o3, and the cir* cuit arrangement is the same as that shown, for example, in Fig.- 1. In this case the microphone box. is also provided with suffiit mica linsulation. toinsure the desired ln Fig. G, the construction and mode ot operation are substantially the same r shown in 1 2 .2 eicciiotie o 'LY- 1 to the (in e, the construe the une and l ,irciiit "Hf that tion inf- -atisfactory results, and will.

The said front and insulations, whereby the transmitter mayy I lig. 5, exceot that in this case' same as that shown in Fig. t,except that the front of the microphone boris omitted. The circuit arrangen'ient may be the Vsame as that shown in F ig. 1, or of any other suit-able character. Fig. 8 shows a construe tion and mode of operation substantially the same as that shown in Fig. 7, with the eX ception that in this case the microphone is composed of a box a, the end wall of which.

is secured to the diaphragm a, and operated opposite sides of the diaphragm. In Fig. i

9, however, the' microphone is made 'u of y two sheet metal boxes a2 and a21 which ave their backs'- or end walls secured to opposite sides ofthe end Wall, and which have.. their -open ends secured by caps or closures a and o23.- The'circuit arrangement for-Fig. 9 is the same as that of Fig. 4.' I.

Thereceiver B', asv shown in Fi 10, com prisesla permanent magnet b', t e shorter leg of .which is provide .with 'a core or' softl iron pole piece b2, upon which is mounted the coil I). The-longer le of the permanent magnet is provided Wit a shoulder b3 upon which rests thearmatjure b4, that vibrates in 'front of the electro-magnet in responsel to the impulse from the differential transmitter or from the differential repeater. The diapl'iragm b5vis`connected by a'steln b to the lower end of the. lever If, which latterhas A ed upon a. pivoted or tilting arm b1, beingadapted to tilt about an axis at .the point b, when the screw '61? is'adjusted one ,way or the other. A spring b13 surrounds the screw 512 and keeps the arm b normally vraised'. W'hen the screw 60 is operated, it raises or lowers thejfulcrumhbs, and thereby changes the leverageof the lever bh When thescrew bn .is operated, it moves-the fulcrum toward o1 away from the diaphragm, so as to regulate or change the air gap between thevvv armature b4 and the core b2 to insure.thefdesired results. 4'The lever 717 is connected withthe `upper end Vof the said' arnuiture h4 by, a' link b, whereby the vibrations of -said armature are'V connected through the variable leverage connection to the iliaphragm-of the receiver. The said variable leverage connectiorrserics to amfpliity the vibrations produced in the receiver in response to the differential action of the a Very deli- It comprises a microphone having front fandV back electrodes g and' gf, a middle or intermediate electrode g2, with granular car-- b on g-betweem-the said front and back electrodes 'closing' thev opposite ends of a boX formed bylalava ring g4... `The electrode g? is carried on aj stem4 gfthat extends through the 'microphone, wliereby the electrode g2 is movableV While tl'ie otbers are stationary.

Thel permanent magnet g6 has its. shorter.

leg proy'idedw-ith a soft iron core or pole piece g?, upon whichv is mounted the coil G.

The longer leg of'thepermanenti-magnet is 4 reststhe armaturefggthat vibrates in front, of the 'softiron-coreor pole piece. This armatureis'connected with a stem g?, and

tl`1e 'outer end ofthedatter is'A provided with means Vfor engaging a lever 919, which latter `has. its -i1ppe r.end s-up'prtedin a fulcr'um g 1. -The said fulcrum' 'consistsof ahollow screw disposed vertically in the support gn spring 91.2 that carried on a 'pi-voted block or army-13, 'which latter is providedwith an' adjusting 'screw "gD- that extends theretlro'ugh and engages the face'orouter surface vofA thegniicrophonevbox. `By adjusting the sci-ew g4?. the airgap' between the arm'ature g andthe core or pole piece 9 7 can be regulated' 'orA changed at'. will toinsure the-best results; .l Vhen the screw or thread- ;'ed fulcrum glofis raised or lowered, 1t

changesgtheleverage 'of the lever g1g, and in; ,tliis 'way the'instrui'nent can beV regulatedvv or: -d'j usted 1 accordance v with 'the strength 0f the current, the character ofthe impulses,

.0r in 'accordance with any other conditions that fire net always the saine in vdii'ierent cases; Mica insulation is applied to the outfside o'-thebox, in the manner shown, to not vonly-insulatelthe microphone from thel magy highly satisfactory manner. Itwill also. be

"1iet .js ,tructure,4 butalso to prevent the instrufment. from being damaged by the heat of4 '.flreaf'ycurrents, it being necessary, in a sys- `if`tem ve ,tiem-:

bodying'the principles of my invento. sometimes use, muchheavier cur'- -rer'itsf than is ordinarily employed in the use of telephone systems.

- 1-From the foregoing, it will be seen that I' havev combined the diierential microphone With aloud-'speaking' receiver, and thatthe 'differential action is used for loud speaking, "or other similar prposes', 1n an etlicient and -'f' seen-that'Iiemploy the differential microphone for'the 'purpose of obtalningclear i '-.uan'd -smoothenunciation and purity of tone,

rather 4z'tliaii for the purpose of increasing adjustmentv ot the parts f the power ofthe transmission. `,In a' Aloud speaking system it is'very essential, I ind` that the enunciation be perfectly clear and smooth, and that the tones be pure and good, as 'a system of this lrind isoften nec- .essarily employed forthe transmission'of music, Aeither vocalv or instrumental. The differential action of themicrophone is ampliiiedin the receiver, 'with the result that the'tones oi either voice or' musical instrument may be heardfor some distance from the said receiver.' The variable leverage system of adJustment forv the repeaters and receivers, in a system Aof this kind, is, I find,

very eiiicient and entirely satisfactory, asby'such method a very, accurate adjustmentis insured, andthe best results are obtained'.

Vfhatl claim as iny invention is: l. In a telephone system, a differential microphone comprising' a pair .of electrodes and a third electrodemovable relatively vto said first-'mentioned electrodes, a. battery and a line circuit, al connection fronrsaid' third electrode to one side of said line, a

connectionffroni each of said other electrodes to opposite sides of said battery, Vand an inductive connection from the opposite side 0fsaid line circuit to -said battery.

2. In a telephone. system', 'a differentialy microphone comprising a pair of`,electrodes 4'and a third electrode movable relatively to said-first-mentioned electrodes, a battery and aline circuit, a connection from said third' `electrode toone slde of said l1 tion from each of said otherelectrodes 'to y,opposite sides of said batter-y,"and an induc-l ltive connection from the opposite side of said line circuit to both 'sides of said battery.

' .3. In a telephone 'syst-em, a -diii'ei'ential microphone, a line circuit, and a source of current, operatively .connected to both sides a conneeioo of said line circuit, a' plurality ofelectrodes i for said transmitter, a connection from one of said electrodes to one side of saidline cir# cuit, vand connect-ions vfrom two other of said electrodes to opposite sides of said source of current, and a. bridge including resistance across said last two connections.

4. ln a telephonesystem, a differential mi- I crophone, a line circuit andasource of current,.operatiifely. connected to both sides of said line circuit, a plurality of electrodes for said. transmitter,` a connection from. one of said electrodes to one side of said line circuit, i

connections from two other ,of' said electrodes to 'opposite sides of, said source of current, andan inductive last two connections.

In-'a telephone system, differential- -microphone, line circuit and a source of current, a plurality of electrodes for said transmitter, a connection from oneofisaid electrodes to -one side ,of said line circuit, connections from twoother of 'saidelectrodes to opposite sidesos'a'id source .of current,

bridge across said :in intlnctivo bridge across said last two con-'v nrt-ti is. :intl a connection from a mid-pointJ ot' usr-.nl inductive bridge to tlio opposite sidov ol saitl lino circuit.

t, in a telephone system, a. line circuit, a 'rntial transmitter7 comprising` a pair of s :itimiary electrodos an'tl a movable elociroile :intl a connection from said movable olt'icl'rode to one side of sa-iclliiic circuit, a source of -cm'rent and connections `froml said 'stationary electrodes 'to opposite sides of 'ce et' current, a bridge across said i connoctionsa pair of conden'se'rs in.

sa itl 'si ,a--aitl bridge. and a connection 4ironia` point said condensers to the opposite side ot' saitlv linocilcnit, and a bridge inclmling resistance across saitlconnections between said inductive bridge and saidv stationary electrode. i

S. In a telephonev system, a line circuit, a-

lill'ci'cntial transmitter, Comprising a pair of stationary electrodes and a movable elec` troclc, a connectionfrom saidmovable elcc trod@ to one side of said line circnitg'a source 'cnrrent and connections from said sta- 't-ionary electrodesto'opposite sides of-said source of current, a bridge across said last4 two connectionsga pair'of condensers in said bric O'e. a connection from a Joint between said y@micio-users to theI opposite side of said line circuit, andv a resistance connected in series with cach of said connections'between the source of current and said :il/itlnctiie bridge. f j i Signed by me lat Chicago, Illinoisf this rtlday oitE November, 1910 

